JP2005232580A - Split sputtering target - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sputtering target of a large size which has low manufacturing cost and permits high-speed sputtering. <P>SOLUTION: The large-sized sputtering target is produced by joining together a plurality of the targets by using metallic foil containing part or whole of component elements of the targets or cooling plates, or metallic foil of the material of which the dielectric constant, magnetic permeability, and thermal conductivity are the same as or similar to those of the targets or the cooling plates. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

Detailed Description of the Invention

The present invention relates to a split sputtering target for forming a thin film.

  Sputtering is a method in which Ar ions collide with a sputtering target at an atomic level in a vacuum, and the constituent elements of the target thus peeled are deposited on the opposing substrate, the energy of which is a direct current or alternating electric field, In some cases, both AC and AC electric fields are used.

  When a sputtering target is used for film formation, it is necessary to cool the target in order to prevent the temperature of the target from rising. There are direct cooling methods and indirect cooling methods for cooling, but the direct cooling method is mainly used for production. In the direct cooling method, the solder selected by the target type, input high frequency power, bias voltage, etc. Or the sputtering target joined to the cooling plate using nonelectroconductive resin etc. is used.

  With the recent increase in the size of sputtering devices, the increase in the size of sputtering targets leads to an increase in manufacturing costs, and the production of large sputtering targets results in an increase in device sales costs. In such a case, a method of manufacturing a small sputtering target, connecting it like a tile to make a large sputtering target, and bonding it to a cooling plate is effective and generally performed.

  However, in this method, since the joining material such as solder used for joining the target and the cooling plate penetrates in the direction of the sputtering surface or capillarity from the joint between the target and the target, Ar is used during sputtering. Since the bonding material is peeled off by the collision of ions and is deposited on the substrate on which the film is formed, it causes impurities in the film.

  Therefore, conventionally, as shown in Japanese Patent No. 2,939,751, etc., by using a heat-resistant resin tape or by providing an angle on the divided joint surface, the bonding material such as solder goes up the gap at the joint portion of the divided sputtering target. I was blocked from going.

  Further, the split target may require bonding by a customer with a gap provided for reasons of the structure of the sputtering apparatus. Even in this case, the resin or the resin tape such as polyimide or Teflon that prevents the solder or the resin from rising from the gap is exposed, and the formed substrate may not exhibit the intended function. In order to prevent this problem, the resin tape and the solder component therebelow in the exposed portion of the cooling plate have been mechanically deleted.

Problems to be solved by the invention

  Although the original purpose was achieved to some extent by using a resin tape such as polyimide, there were the following major drawbacks. In other words, since resin tapes such as polyimide and Teflon have poor thermal conductivity, the cooling efficiency of the target of the part where the resin tape is used is reduced, so that a partial temperature rise occurs, and the bonding with the cooling plate Solder melts out, causes cracking or chipping of the target, and in the case of an oxide target, oxygen is easily released, and the dielectric constant lowers partially and electric field concentration occurs, causing abnormal discharge. . As a result, the input sputtering power is limited.

  In addition, when solder is used for joining the split sputtering target and the cooling plate, the wettability of the resin tape and the solder is poor, and in particular, the use of Teflon tends to promote the above characteristics due to the property of repelling the solder. And the adhesion of the cooling plate is significantly reduced. In particular, when a gap is intentionally provided between the split sputtering targets, great manufacturing difficulties have also occurred.

Means for solving the problem

  The split sputtering target of the present invention is characterized by using an appropriate metal foil at the joint, and there is no resin or the like that easily evaporates during sputtering in the gap, or even if a slight amount of adhesive resin remains, Due to the good thermal conductivity, it was possible to prevent the resin from evaporating to a minimum, thus preventing abnormal discharge, and as a result, the input power during sputtering could be improved. It was also found that the sputtering target can be consumed uniformly by making the physical constants such as the dielectric constant the same or approximate.

  Examples of the metal foil that can be used include a material that includes part or all of the composition elements of the target or the cooling plate. For example, a titanium foil for a titanium oxide target, a copper foil for a copper cooling plate, and the like. A material having the same or similar dielectric constant, magnetic permeability and thermal conductivity as the target or cooling plate can also be used. The approximate material includes, for example, a 98% pure titanium foil with respect to a 99.99% pure titanium target.

  FIG. 1 is a cross-sectional view of a joint portion of the split sputtering target of the present invention. In either case, the joint portion of the split sputtering target is coated with a metal foil from the opposite side of the sputtering surface and then bonded to the cooling plate. As a result, solder and resin for cooling plate bonding are not exposed and the gap at the joint portion is not raised.

  FIG. 2 is a cross-sectional view of the joint portion when the gap between the split sputtering targets is intentionally opened. It has been found that removal of the resin and solder in the gaps necessary when connecting with a non-metal foil is unnecessary and is particularly effective.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely using an Example, the scope of the present invention is not limited by an Example.

  Two titanium plates having a width of 127 mm, a length of 508 mm, and a thickness of 6 mm were covered with a titanium foil and bonded to each other using a polyimide adhesive. This was joined to the cooling plate using indium solder utilizing ultrasonic waves.

  The divided sputtering target thus produced was attached to a DC magnetron sputtering apparatus, and a titanium film was formed on a glass substrate at an applied voltage of 500 V. As a result, a titanium film could be produced at a deposition rate of 180 nm / min.

Comparative Example 1

  Except for using a polyimide sheet in place of the titanium foil, the same split sputtering target as in Example 1 was prepared and attached to a sputtering apparatus, and a titanium film was formed on a glass substrate under the same conditions as in Example 1. As a result, abnormal discharge occurred 5 minutes after the start of film formation. When the film formation was stopped and the sputtering target was taken out, the indium solder near the joint portion melted, and a space was created between the target and the cooling plate. It was.

  A split sputtering target composed of three titanium oxide plates having a width of 127 mm, a length of 254 mm, and a thickness of 6 mm was covered with a titanium foil and bonded together with an acrylic adhesive. When this was joined to the cooling plate with a thermosetting silicone resin at 150 ° C., the resin did not enter the two joints, and the cooling plate and the split target could be joined well. Since the divided part of the divided sputtering target is covered with titanium foil, the influence of the silicon resin for joining with the cooling plate is completely eliminated.

  This split sputtering target was attached to an RF sputtering apparatus, and when a titanium oxide film was formed on a glass substrate for 10 minutes at an applied voltage of 500 V, a uniform titanium oxide film having a thickness of 300 nm could be produced. No change was observed in the joint portion of the split sputtering target taken out after film formation.

Comparative Example 2

  Except for using a Teflon sheet instead of a titanium foil, an attempt was made to produce a split sputtering target in the same manner as in Example 2. However, the adhesive strength between the Teflon sheet and the target was weak, and the adhesive strength between the cooling plate was insufficient. .

  When this divided sputtering target was attached to an RF sputtering apparatus and an attempt was made to form a titanium oxide film for 10 minutes at an applied voltage of 500 V on a glass substrate, a titanium oxide film having a thickness of 340 nm could be produced. When the joint portion of the split sputtering target taken out after film formation was observed, some fine cracks were found in the target.

  A copper foil having a thickness of 0.02 mm was cut into a strip having a width of 10 mm and a length of 150 mm. A heat-resistant silicon-based curing agent (heat-resistant temperature: 200 ° C.) was applied in a strip shape of 4 mm from both ends to a width of 10 mm. Using this, three split sputtering targets (made of silicon) of 90 mm width and length of about 150 mm were bonded and cured with a 3 mm gap. The joined split silicon sputtering target was bonded to an oxygen free copper cooling plate with indium solder and solidified. At the joint portion of the split silicon sputtering target having a width of 3 mm, infiltration of the indium solder into the sputter surface was not observed, and a copper foil having the same quality as that of the cooling plate was visually observed.

  This split sputtering target was attached to a DC magnetron sputtering apparatus and an attempt was made to form a silicon film on a silicon substrate. When a film was formed at an applied voltage of 500 V for 5 minutes, a silicon film with a thickness of 600 nm was produced.

Comparative Example 3

  A split sputtering target was prepared in the same manner as in Example 3 except that a polyimide sheet was used instead of the copper foil, and the polyimide sheet was visually confirmed at the joint.

  This split sputtering target was attached to a sputtering apparatus, and an attempt was made to form a silicon film on a silicon substrate. When a film was formed at an applied voltage of 500 V, abnormal discharge occurred 2 minutes after the start of film formation. When the film formation was stopped and the sputtering target was taken out, it was visually confirmed that the target near the joint was missing. It was.

The invention's effect

  According to the present invention, clean sputtering was realized by using a metal foil of the same quality as possible in the split sputtering target at the joint portion. It has been found that aluminum foil, copper foil, titanium foil, etc. can be used freely depending on the method of use. The adhesive strength and cooling capacity were enhanced by the use of metal foil, and it was found that the magnetron sputtering method does not disturb the magnetic field at all. As a result, the voltage applied to the sputtering target can be increased, which contributes to high-speed sputtering and improves the economic efficiency, thereby helping to reduce waste to the environment.

It is the figure which showed the cross section of the joint part of the division | segmentation sputtering target produced by joining a metal foil with a thermosetting resin, and then joining with a cooling plate with a joining material. It is the figure which showed the cross section of the joint part of the division | segmentation sputtering target by which the clearance gap was intentionally opened at the joint.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sputtering target 2 Joining material 3 Thermosetting resin 4 Metal foil 5 Cooling plate

Claims (5)

In a split sputtering target prepared by joining two or more sputtering targets composed of ceramic or metal and a mixture thereof, a high temperature is obtained by covering the joint of two or more sputtering targets with a metal sheet from the surface joining the cooling plate. A split sputtering target characterized by having an integrated shape by joining and joining with solder or heat-resistant resin. 2. The divided sputtering target according to claim 1, wherein the metal sheet is made of the same material as part or all of the components of the sputtering target or the cooling plate to be joined. 2. The split sputtering target characterized in that the metal sheet according to claim 1 is made of a material having a dielectric constant, magnetic permeability, and thermal conductivity that is similar to or similar to a sputtering target or a cooling plate to be soldered. The split sputtering target according to claim 2 or 3, characterized in that the gap between the individual target joints is intentionally spaced. The split sputtering target according to claim 1, wherein the split sputtering target has a shape joined to a cooling plate using solder or a heat-resistant resin.

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